Evolved antenna
Antenna designed by evolutionary algorithms for demanding requirements.
An evolved antenna is an antenna whose design is created entirely or mostly by a computer program running an evolutionary algorithm—a process that simulates Darwinian natural selection. This approach has been employed since the early 2000s for mission-critical tasks with demanding, conflicting, or unconventional specifications, such as unusual radiation patterns, where existing antenna types fall short.
The design process begins with simple antenna shapes. The program then adds or modifies elements in a partly random way to generate a set of candidate designs. Each candidate is tested against the requirements and given a numerical score. In a step akin to natural selection, the lowest-scoring designs are discarded, leaving a smaller group of top performers. Using these survivors, the program repeats the cycle—applying operations like mutation, crossover, and selection—to produce a new generation, again keeping the best. After many iterations, the highest-scoring design from the final population is chosen. The resulting antenna often surpasses the best human-made designs because it takes a complex, asymmetric form that traditional manual methods could not discover.
The first evolved antennas emerged in the mid-1990s from the work of Michielssen, Altshuler, Linden, Haupt, and Rahmat-Samii. Most practitioners use the genetic algorithm technique or a similar variant to evolve antenna designs.
One example is an X-band antenna evolved for NASA's Space Technology 5 (ST5) mission in 2006. The mission aimed to test innovative technologies for future spaceflight. Each of the mission’s satellites carried two communication antennas to link with ground stations: an evolved antenna with an unusual structure and a more standard quadrifilar helix antenna. The evolved antenna was designed to meet a challenging set of requirements, notably a wide beamwidth for circularly polarized waves combined with a wide impedance bandwidth covering both up and down link frequencies at X-band. Both antennas were built by the Physical Science Laboratory at New Mexico State University. Externally, they looked nearly identical, as a foam radome covered the radiating elements. The ST5 mission launched successfully on March 22, 2006, operated for its planned period, and was then decommissioned by NASA. This made the evolved antenna the first artificially evolved object to fly in space.
- First evolved antenna designs appeared
- mid-1990s
- Pioneering researchers
- Michielssen, Altshuler, Linden, Haupt, Rahmat-Samii
- Example mission
- Space Technology 5 (ST5)
- Mission launch date
- March 22, 2006
- Mission operator
- NASA
- Fabrication site
- Physical Science Laboratory at New Mexico State University
- Subsequent mission
- Lunar Atmosphere and Dust Environment Explorer
Lore & Background
The process begins with simple antenna shapes, then adds or modifies elements in a semirandom manner to create candidate designs. These are evaluated against design requirements, and a numerical score is computed for each. In a step similar to natural selection, a portion of the worst-scoring candidates are discarded, leaving a smaller population of the highest-scoring designs. The computer repeats the procedure, generating successive populations using operators such as mutation, crossover, and selection, until the highest-scoring design is chosen. The resulting antenna often outperforms the best manual designs because it has a complicated asymmetric shape that could not have been found with traditional manual design methods.
The first evolved antenna designs appeared in the mid-1990s from the work of Michielssen, Altshuler, Linden, Haupt, and Rahmat-Samii. Most practitioners use the genetic algorithm technique or some variant thereof. An example is an X-band antenna evolved for the 2006 NASA Space Technology 5 (ST5) mission. Each satellite had two communication antennas: an evolved antenna with unusual structure and a more standard quadrifilar helix antenna. The evolved antenna was designed to meet a challenging set of mission requirements, notably the combination of wide beamwidth for circularly polarized waves and wide impedance bandwidth to cover up and down link frequencies at X-band. Both antennas were fabricated by the Physical Science Laboratory at New Mexico State University, and their external appearance was essentially identical because a foam radome covered the radiating elements.
Reader's Guide
The ST5 mission successfully launched on March 22, 2006, and operated for the mission period before being decommissioned by NASA. This evolved antenna represents the world's first artificially-evolved object to fly in space. Its success demonstrated that evolutionary algorithms could produce practical, flight-qualified hardware for demanding space applications. The approach proved especially valuable for requirements that are stringent, conflicting, or unusual—such as the combination of wide beamwidth and wide impedance bandwidth—where traditional antenna types are inadequate. The ST5 antenna's complicated asymmetric shape, which could not have been found with manual methods, outperformed the best manual designs. Subsequent evolved antennas were used on the Lunar Atmosphere and Dust Environment Explorer spacecraft, further validating the technique for mission-critical roles. The legacy of evolved antennas lies in establishing a new design paradigm: instead of relying on human intuition and existing antenna types, designers can now task computers to explore vast, unconventional design spaces and produce solutions that meet exacting specifications. This has opened the door to antennas for future space missions and other applications where conventional designs fall short.
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